Several temperature-sensitive mutant strains of E. coli display the following characteristics. Predict what enzyme or function is being affected by each mutation. No initiation occurs.

Key Concepts

Gene Expression Regulation

Gene expression regulation involves the processes that control the timing and amount of gene product (RNA or protein) produced in a cell. In bacteria like E. coli, this regulation is crucial for responding to environmental changes, including temperature. Mutations affecting initiation can disrupt the transcription or translation processes, leading to a failure in producing necessary proteins.

Transcription Initiation

Transcription initiation is the first step in gene expression, where RNA polymerase binds to the promoter region of a gene to begin synthesizing RNA. In E. coli, this process requires specific proteins and factors, such as sigma factors, to recognize the promoter. Mutations that affect these components can prevent the initiation of transcription, resulting in no RNA production.

Temperature-Sensitive Mutations

Temperature-sensitive mutations are genetic alterations that result in a functional protein at one temperature but not at another. In the context of E. coli, these mutations can affect enzymes or proteins involved in critical cellular processes, such as transcription initiation. At non-permissive temperatures, these mutations can lead to a complete halt in essential functions, such as the initiation of gene expression.